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Developmental Biology Oct 2014The kidney is a homeostatic organ required for waste excretion and reabsorption of water, salts and other macromolecules. To this end, a complex series of developmental...
The kidney is a homeostatic organ required for waste excretion and reabsorption of water, salts and other macromolecules. To this end, a complex series of developmental steps ensures the formation of a correctly patterned and properly proportioned organ. While previous studies have mainly focused on the individual signaling pathways, the formation of higher order receptor complexes in lipid rafts is an equally important aspect. These membrane platforms are characterized by differences in local lipid and protein compositions. Indeed, the cells in the Xenopus pronephric kidney were positive for the lipid raft markers ganglioside GM1 and Caveolin-1. To specifically interfere with lipid raft function in vivo, we focused on the Sterol Carrier Protein 2 (scp2), a multifunctional protein that is an important player in remodeling lipid raft composition. In Xenopus, scp2 mRNA was strongly expressed in differentiated epithelial structures of the pronephric kidney. Knockdown of scp2 did not interfere with the patterning of the kidney along its proximo-distal axis, but dramatically decreased the size of the kidney, in particular the proximal tubules. This phenotype was accompanied by a reduction of lipid rafts, but was independent of the peroxisomal or transcriptional activities of scp2. Finally, disrupting lipid micro-domains by inhibiting cholesterol synthesis using Mevinolin phenocopied the defects seen in scp2 morphants. Together these data underscore the importance for localized signaling platforms in the proper formation of the Xenopus kidney.
Topics: Animals; Anticholesteremic Agents; Body Patterning; Carrier Proteins; Cell Line; Cholesterol; Gene Knockdown Techniques; HEK293 Cells; Humans; Kidney Tubules, Proximal; Lovastatin; Membrane Microdomains; Morpholinos; RNA, Messenger; Transcription, Genetic; Xenopus Proteins; Xenopus laevis
PubMed: 25127994
DOI: 10.1016/j.ydbio.2014.07.025 -
IARC Scientific Publications 1978Pronephric tumor cell lines have been established from tumours induced after inoculation of embryos with herpesvirus cultivated in vitro. Neoplastic properties of the...
Pronephric tumor cell lines have been established from tumours induced after inoculation of embryos with herpesvirus cultivated in vitro. Neoplastic properties of the lines are characterized.
Topics: Animals; Antigens, Viral; Anura; Cell Line; Herpesviridae Infections; Herpesvirus 1, Ranid; Kidney Neoplasms; Neoplasm Transplantation; Neoplasms, Experimental; Rana pipiens; Transplantation, Homologous; Tumor Virus Infections
PubMed: 221384
DOI: No ID Found -
Pediatric Nephrology (Berlin, Germany) May 2000The zebrafish, as a model system for vertebrate development, offers distinct experimental advantages for studies of organogenesis. The simplicity of the zebrafish... (Review)
Review
The zebrafish, as a model system for vertebrate development, offers distinct experimental advantages for studies of organogenesis. The simplicity of the zebrafish pronephros, the feasibility of isolating large numbers of mutants, and the growth in infrastructure for genomics makes the zebrafish an attractive system for the analysis of kidney development. Mutants affecting several aspects of nephrogenesis, including differentiation of the intermediate mesoderm, nephron patterning, epithelial polarity, and angiogenesis, have been isolated. Analysis of mutant phenotypes and the cloning of mutant genes has revealed: (1) a role for bone morphogenetic proteins in patterning the ventral mesoderm, (2) an essential role for the pax2.1 gene in pronephric development, (3) multiple loci required for establishing epithelial polarity in the pronephric duct, (4) a central role for podocytes in directing glomerulogenesis, and (5) 15 loci associated with cystic maldevelopment in the pronephros. The striking similarities of pronephric cell types to those found in higher vertebrates, as well as the conservation of kidney-specific gene expression patterns, suggest that insights gained from studies in zebrafish will be broadly applicable to cell differentiation in the kidney.
Topics: Animals; Embryo, Nonmammalian; Genetic Techniques; Mesoderm; Mutation; Neovascularization, Physiologic; Nephrons; Zebrafish
PubMed: 10805474
DOI: 10.1007/s004670050788 -
BMC Developmental Biology May 2010Three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. The pronephric duct is the first or primary ureter of these...
BACKGROUND
Three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. The pronephric duct is the first or primary ureter of these kidney systems. Its role as a key player in the induction of nephrogenic mesenchyme is well established. Here we investigate whether the duct is involved in urine modification using larvae of the freshwater amphibian Ambystoma mexicanum (axolotl) as model.
RESULTS
We investigated structural as well as physiological properties of the pronephric duct. The key elements of our methodology were: using histology, light and transmission electron microscopy as well as confocal laser scanning microscopy on fixed tissue and applying the microperfusion technique on isolated pronephric ducts in combination with single cell microelectrode impalements. Our data show that the fully differentiated pronephric duct is composed of a single layered epithelium consisting of one cell type comparable to the principal cell of the renal collecting duct system. The cells are characterized by a prominent basolateral labyrinth and a relatively smooth apical surface with one central cilium. Cellular impalements demonstrate the presence of apical Na+ and K+ conductances, as well as a large K+ conductance in the basolateral cell membrane. Immunolabeling experiments indicate heavy expression of Na+/K+-ATPase in the basolateral labyrinth.
CONCLUSIONS
We propose that the pronephric duct is important for the subsequent modification of urine produced by the pronephros. Our results indicate that it reabsorbs sodium and secretes potassium via channels present in the apical cell membrane with the driving force for ion movement provided by the Na+/K+ pump. This is to our knowledge the first characterization of the pronephric duct, the precursor of the collecting duct system, which provides a model of cell structure and basic mechanisms for ion transport. Such information may be important in understanding the evolution of vertebrate kidney systems and human diseases associated with congenital malformations.
Topics: Ambystoma mexicanum; Animals; Biological Evolution; Ion Transport; Ureter
PubMed: 20507566
DOI: 10.1186/1471-213X-10-56 -
Development (Cambridge, England) May 2009Cilia defects have been implicated in a variety of human diseases and genetic disorders, but how cilia motility contributes to these phenotypes is still unknown. To...
Cilia defects have been implicated in a variety of human diseases and genetic disorders, but how cilia motility contributes to these phenotypes is still unknown. To further our understanding of how cilia function in development, we have cloned and characterized two alleles of seahorse, a zebrafish mutation that results in pronephric cysts. seahorse encodes Lrrc6l, a leucine-rich repeat-containing protein that is highly conserved in organisms that have motile cilia. seahorse is expressed in zebrafish tissues known to contain motile cilia. Although mutants do not affect cilia structure and retain the ability to interact with Disheveled, both alleles of seahorse strongly affect cilia motility in the zebrafish pronephros and neural tube. Intriguingly, although seahorse mutations variably affect fluid flow in Kupffer's vesicle, they can have very weak effects on left-right patterning. Combined with recently published results, our alleles suggest that the function of seahorse in cilia motility is separable from its function in other cilia-related phenotypes.
Topics: Amino Acid Sequence; Animals; Body Patterning; Cilia; Molecular Sequence Data; Mutation; Neural Tube; Zebrafish; Zebrafish Proteins
PubMed: 19395640
DOI: 10.1242/dev.020735 -
Developmental Biology Sep 2008The pronephros is the first kidney to develop and is the functional embryonic kidney in lower vertebrates. It has previously been shown that pronephric tubules can be... (Comparative Study)
Comparative Study
The pronephros is the first kidney to develop and is the functional embryonic kidney in lower vertebrates. It has previously been shown that pronephric tubules can be induced to form ex vivo in ectodermal tissue by treatment with activin A and retinoic acid. In this study, we investigated the role of Ca(2+) signaling in the formation of the pronephric tubules both in intact Xenopus embryos and ex vivo. In the ex vivo system, retinoic acid but not activin A stimulated the generation of Ca(2+) transients during tubule formation. Furthermore, tubule differentiation could be induced by agents that increase the concentration of intracellular Ca(2+) in activin A-treated ectoderm. In addition, tubule formation was inhibited by loading the ectodermal tissue with the Ca(2+) chelator, BAPTA-AM prior to activin A/retinoic acid treatment. In intact embryos, Ca(2+) transients were also recorded during tubule formation, and photo-activation of the caged Ca(2+) chelator, diazo-2, localized to the pronephric domain, produced embryos with a shortened and widened tubule phenotype. In addition, the location of the Ca(2+) transients observed, correlated with the expression pattern of the specific pronephric tubule gene, XSMP-30. These data indicate that Ca(2+) might be a necessary signal in the process of tubulogenesis both ex vivo and in intact embryos.
Topics: Activins; Animals; Calcium; Cell Differentiation; Chelating Agents; DNA Primers; Diazonium Compounds; Immunohistochemistry; In Situ Hybridization; Kidney Tubules; Microdissection; Phenoxyacetates; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Tretinoin; Xenopus laevis
PubMed: 18634776
DOI: 10.1016/j.ydbio.2008.06.029 -
International Journal of Molecular... Nov 2015The kidneys play a physiologic role in the regulation of urine formation and nutrient reabsorption in the proximal tubule epithelial cells. Kidney development has been... (Review)
Review
The kidneys play a physiologic role in the regulation of urine formation and nutrient reabsorption in the proximal tubule epithelial cells. Kidney development has been shown to be regulated through calcium (Ca2+) signaling processes that are present through numerous steps of tubulogenesis and nephron induction during embryonic development of the kidneys. Ca2+-binding proteins, such as calbindin-D28k and regucalcin are important proteins that are commonly used as biomarkers in pronephric tubules, and the ureteric bud and metanephric mesenchyme. Previous research on regucalcin focused on Ca2+ sensors that are involved in renal organogenesis and the link between Ca2+-dependent signals and polycystins. Moreover, regucalcin has been highlighted to play a multifunctional role in kidney cell regulation. The regucalcin gene, which is localized on the X chromosome, is regulated through various transcription factors. Regucalcin has been found to regulate intracellular Ca2+ homeostasis in kidney proximal tubule epithelial cells. Regucalcin has been demonstrated to regulate the activity of various enzymes that are involved in intracellular signaling pathways. It has been noted that regucalcin suppresses DNA synthesis and regulates the gene expression of various proteins related to mineral transport, transcription factors, cell proliferation and apoptosis. The overexpression of regucalcin has been shown to exert suppressive effects on cell proliferation and apoptotic cell death, which are stimulated by various stimulatory factors. Moreover, regucalcin gene expression was found to to be involved in various pathophysiological states, including renal failure. This review discusses recent findings concerning the potential role of regucalcin as a regulatory protein in the kidney proximal tubule epithelial cells.
Topics: Animals; Epithelial Cells; Gene Expression; Homeostasis; Humans; Kidney; Renal Insufficiency; Signal Transduction
PubMed: 26398287
DOI: 10.3892/ijmm.2015.2343 -
Tissue & Cell 1991Embryos of lampreys Petromyzon marinus were obtained through a technique of artificial fertilization. Samples of developmental intervals to the prolarval stage were...
Embryos of lampreys Petromyzon marinus were obtained through a technique of artificial fertilization. Samples of developmental intervals to the prolarval stage were prepared for transmission electron microscopy and the pronephros was examined. The pronephros was visible in the cardiac region of the coelom prior to the time of hatching of embryos and consisted of a renal corpuscle, nephrostomes, and proximal tubules connected to a pronephric duct. The renal corpuscle was comprised of poorly-defined vascular channels and a visceral epithelium of yolk-filled cells, the podocytes, with short major processes and pedicels resting on a basal lamina. The first proximal tubules possessed a delicate brush border of short microvilli but subsequent cellular differentiation yielded cells with all the components required for the process of endocytosis, a process which was demonstrated by uptake of the tracer, horseradish peroxidase. The distal tubules appeared later in development and were noted for abundant mitochondria and an extensive smooth tubular network. The timing of differentiation of various components of the nephron corresponds to that seen during morphogenesis of other vertebrate kidneys.
PubMed: 18621169
DOI: 10.1016/0040-8166(91)90057-z -
Current Opinion in Nephrology and... Jul 2011The zebrafish pronephros provides an informative vertebrate model system for studying renal development and function as well as a rapid screening tool for identification... (Review)
Review
PURPOSE OF REVIEW
The zebrafish pronephros provides an informative vertebrate model system for studying renal development and function as well as a rapid screening tool for identification of genes important to the physiology and pathophysiology of the vertebrate kidney. To this end, the zebrafish pronephros is continuously being characterized and its relevance for the study of human diseases validated. This review summarizes recent advances in our current knowledge of the zebrafish pronephros as a valuable model system relevant to the study of human kidney biology and nephropathology.
RECENT FINDINGS
Recent findings argue for conserved renal gene structure and function in the zebrafish pronephros and also elucidate the role of genes in kidney biology that were not possible to discern in other vertebrate model systems due to early lethality.
SUMMARY
Abnormalities in podocyte gene function, renal ion channels and transporters, and renal epithelial primary cilia genes lead to defective pronephric kidney function in the zebrafish that mimics human disease. This supports the use of the zebrafish pronephros as a valid system to study kidney physiology and for rapid identification of potential therapeutic drugs and strategies in combating renal disease.
Topics: Animals; Disease Models, Animal; Gene Expression Regulation; Humans; Ion Transport; Kidney; Kidney Diseases; Stem Cells; Zebrafish; Zebrafish Proteins
PubMed: 21519251
DOI: 10.1097/MNH.0b013e3283477797 -
Developmental Biology Sep 2005Podocytes are specialized cells of the kidney that form the blood filtration barrier in the kidney glomerulus. The barrier function of podocytes depends upon the... (Comparative Study)
Comparative Study
Podocytes are specialized cells of the kidney that form the blood filtration barrier in the kidney glomerulus. The barrier function of podocytes depends upon the development of specialized cell-cell adhesion complexes called slit-diaphragms that form between podocyte foot processes surrounding glomerular blood vessels. Failure of the slit-diaphragm to form results in leakage of high molecular weight proteins into the blood filtrate and urine, a condition called proteinuria. In this work, we test whether the zebrafish pronephros can be used as an assay system for the development of glomerular function with the goal of identifying novel components of the slit-diaphragm. We first characterized the function of the zebrafish homolog of Nephrin, the disease gene associated with the congenital nephritic syndrome of the Finnish type, and Podocin, the gene mutated in autosomal recessive steroid-resistant nephrotic syndrome. Zebrafish nephrin and podocin were specifically expressed in pronephric podocytes and required for the development of pronephric podocyte cell structure. Ultrastructurally, disruption of nephrin or podocin expression resulted in a loss of slit-diaphragms at 72 and 96 h post-fertilization and failure to form normal podocyte foot processes. We also find that expression of the band 4.1/FERM domain gene mosaic eyes in podocytes is required for proper formation of slit-diaphragm cell-cell junctions. A functional assay of glomerular filtration barrier revealed that absence of normal nephrin, podocin or mosaic eyes expression results in loss of glomerular filtration discrimination and aberrant passage of high molecular weight substances into the glomerular filtrate.
Topics: Amino Acid Sequence; Animals; Cell Adhesion; Cloning, Molecular; DNA Primers; Eye Proteins; Histocytochemistry; In Situ Hybridization; Intracellular Signaling Peptides and Proteins; Kidney Glomerulus; Membrane Proteins; Microscopy, Electron, Transmission; Molecular Sequence Data; Oligonucleotides; Podocytes; Zebrafish; Zebrafish Proteins
PubMed: 16102746
DOI: 10.1016/j.ydbio.2005.06.038